1. Field of the Invention
The invention relates to a seam construction for joining the ends of a belt, thereby making it endless, and more particularly relates to a spiral seam construction for making endless a flat woven papermakers machine clothing fabricated to include flat monofilament lengthwise (warp) yarns.
2. Brief Description of the Prior Art
The art is replete with descriptions of pin seam constructions for paper makers felts; see for example the disclosures of U.S. Pat. Nos. 2,883,734; 3,436,041; 3,653,097; 4,026,331; 4,006,760; and 4,123,022. The seam construction loops formed along the length of the fabric's lengthwise yarns and extending outwardly from each end of the fabric and anchored in the fabric. The opposing loops are brought together, interleaved and secured together by a cable or pintle passed through the interleafed loops.
A modification of the pin seam is commonly referred to as a "spiral seam". The spiral seam employs, a seaming coil of a single formed monofilament to provide the loops on each side of the seam; see for example U.S. Pat. No. 4,315,049.
In spite of the highly developed state of the seaming art, many problems exist in the practical, day-to-day operation of seamed belts.
One particular problem of prior art seam constructions concerns fabrics possessing flat warp (lengthwise) yarns of polymeric resin monofilaments. These latter belts when made endless with a conventional pin seam are inherently susceptible to flex fatigue and subsequently, a shortened life. We have discovered that this particular problem of the prior art may be alleviated to a degree by the selection and use of a spiral seam.